From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx101.postini.com [74.125.245.101]) by kanga.kvack.org (Postfix) with SMTP id 215746B00B7 for ; Sun, 11 Dec 2011 23:37:07 -0500 (EST) Date: Mon, 12 Dec 2011 15:36:57 +1100 From: Dave Chinner Subject: Re: XFS causing stack overflow Message-ID: <20111212043657.GO14273@dastard> References: <20111209115513.GA19994@infradead.org> <20111209221956.GE14273__25752.826271537$1323469420$gmane$org@dastard> <20111210221345.GG14273@dastard> <20111211000036.GH24062@one.firstfloor.org> <20111211230511.GH14273@dastard> <20111212023130.GI24062@one.firstfloor.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20111212023130.GI24062@one.firstfloor.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andi Kleen Cc: Christoph Hellwig , linux-mm@kvack.org, xfs@oss.sgi.com, "Ryan C. England" On Mon, Dec 12, 2011 at 03:31:30AM +0100, Andi Kleen wrote: > > But that happens before do_IRQ is called, so what is the do_IRQ call > > chain doing on this stack given that we've already supposed to have > > switched to the interrupt stack before do_IRQ is called? > > Not sure I understand the question. > > The pt_regs are on the original stack (but they are quite small), all the rest It's ~180 bytes, so it's not really that small. > is on the new stack. ISTs are not used for interrupts, only for > some special exceptions. IST = ??? > do_IRQ doesn't switch any stacks on 64bit. No, but it appears that it's caller does: /* 0(%rsp): ~(interrupt number) */ .macro interrupt func /* reserve pt_regs for scratch regs and rbp */ subq $ORIG_RAX-RBP, %rsp CFI_ADJUST_CFA_OFFSET ORIG_RAX-RBP SAVE_ARGS_IRQ call \func .endm and the SAVE_ARGS_IRQ macro switches to the per cpu interrupt stack. The only caller does this: common_interrupt: XCPT_FRAME addq $-0x80,(%rsp) /* Adjust vector to [-256,-1] range */ interrupt do_IRQ So, why do we get this: Dec 6 20:27:55 localhost kernel: [] ? warn_slowpath_common+0x87/0xc0 Dec 6 20:27:55 localhost kernel: [] ? __do_softirq+0x11a/0x1d0 Dec 6 20:27:55 localhost kernel: [] ? warn_slowpath_fmt+0x46/0x50 Dec 6 20:27:55 localhost kernel: [] ? call_softirq+0x1c/0x30 Dec 6 20:27:55 localhost kernel: [] ? handle_irq+0x8f/0xa0 Dec 6 20:27:55 localhost kernel: [] ? do_IRQ+0x6c/0xf0 Dec 6 20:27:55 localhost kernel: [] ? ret_from_intr+0x0/0x11 Dec 6 20:27:55 localhost kernel: [] ? kmem_cache_free+0xbf/0x2b0 at the top of the stack frame? Is the stack unwinder walking back across the interrupt stack to the previous task stack? Cheers, Dave. -- Dave Chinner david@fromorbit.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org